1. Field of the Invention
The present invention relates to a vehicle periphery visual confirming apparatus which, under a poor visibility condition, takes a picture of a peripheral scene before or behind a vehicle, or, on the right- or left-side scene of the vehicle, that is, the scene of a blind spot to a driver and displays the picture of the scene to the driver.
2. Description of the Related Art
A conventional vehicle periphery visual confirming apparatus 1, as shown in FIGS. 2 and 7, comprises a picture camera apparatus 11 disposed on a front bumper 17 of a vehicle 16 to take pictures of the two side scenes of the vehicle 16, a mirror image reversal processing part 12 for mirror-image processing picture signals supplied from the picture camera apparatus 11, and a display part 15 disposed within a vehicle room for displaying the picture images obtained from the mirror image reversal processing part 12.
The picture camera apparatus 11 comprises: a lightproof case 3 on the two sides of which there are formed a pair of left and right penetration window portions 2L, 2R; a prism 4 having an isosceles-triangular-shaped section stored in the interior portion of the case 3 and disposed in such an attitude that its vertical angle portion 5 faces the front portion of the case 3 and its left and right prism side surfaces 8L, 8R respectively face the left and right penetration window portions 2L, 2R; and, an imaging device 10 stored and disposed in the rear of the rear surface 8B of the prism 4 through an imaging lens 9.
In this structure, light rays 18L, which have entered from the penetration window portion 2L and have penetrated through the prism side surface 8L, are reflected by the internal surface of the other prism side surface 8R and are then guided through the imaging lens 9 onto the left half surface 10L of the imaging surface of the imaging device 10. On the other hand, light rays 18R, which have entered from the penetration window portion 2R and have penetrated through the prism side surface 8R, are reflected by the internal surface of the other prism side surface 8L and are then guided through the imaging lens 9 onto the right half surface 10R of the imaging surface of the imaging device 10. That is, the pictures of the two right- and left-side scenes can be taken at the same time by the imaging device 10.
And, the image signals of the pictures of the scenes taken by the imaging device 10 are mirror-image-reversal processed by the mirror image reversal processing part 12 and are then output to the display part 15; and, the left-side scene introduced from the penetration window portion 2L into the left half screen 15L of the display part 15 is displayed as the left-side scene images, whereas the right-side scene introduced from the penetration window portion 2R into the right half screen 15R of the display part 15 is displayed as the right-side scene images.
However, actually, as shown in FIG. 7, in the light rays 18R which have entered the vertical angle adjacent area 5R of the prism side surface 8R, there exist light rays such as light rays 18Ra which, after they are reflected by the internal surface of the prism side surface 8L and are penetrated through the imaging lens 9, are not guided to the right half surface 10R of the imaging surface of the imaging device 10 but are guided to a boundary area 10La on the left half surface 10L side. In this case, the light rays 18R of the right-side scene are taken in from the penetration window portion 2L by the imaging device 10 and are mingled with the light rays 18L of the left-side scene guided to the same boundary area 10La, before they are converted into image signals. And, in a boundary area 10Ra on the right half surface 10R side of the imaging surface as well, because they are symmetric, there occurs a similar phenomenon.
As a result of this, there arises the following problem: that is, the images to be displayed on the display part 15, as shown in FIG. 9, are displayed in the screen central portion 23 of the display part 15 in such a manner that the left-side scene images 19L and right-side scene images 19R are overlapped with each other.
The present invention aims at eliminating the above drawbacks found in the conventional vehicle periphery visual confirming apparatus. Accordingly, it is an object of the invention to provide a vehicle periphery visual confirming apparatus capable of preventing one-side scene images and the-other-side scene images from being displayed in such a manner that they are overlapped together in the central portion of the display screen.
In attaining the above object, according to a first aspect of the invention, there is provided a vehicle periphery visual confirming apparatus comprising a picture camera apparatus disposed on the outside of a vehicle, the picture camera apparatus comprising: a case including a pair of right and left penetration window portions respectively formed on the two sides thereof; a prism having an isosceles-triangular-shaped section and disposed within the case in such an attitude that its vertical angle portion faces the front portion of the case and its right and left prism side surfaces corresponding to the two equal sides of its isosceles triangle shape respectively face the right and right penetration window portions; an imaging lens disposed in the rear of the prism rear surface; and, an imaging device which is disposed in the rear of the imaging lens and also which, when light rays entering from one of the right and left prism side surfaces are reflected by the other of the right and left prism side surfaces and are radiated from the prism rear surface of the prism, focuses the light rays onto an imaging surface of the imaging device through the imaging lens to thereby convert the light rays into image signals, characterized by preventive means which is disposed in the vertical angle portion of the prism and also which, when light rays penetrate through one of the penetration window portions and one of the vertical angle adjacent areas of the prism side surfaces sequentially, are reflected by the internal surface of the other-side prism side surface, are radiated from the prism rear surface, and are focused through the imaging lens onto the other-side half surface area of the imaging surface of the imaging device, can be prevent such light rays from advancing into the prism through the vertical angle adjacent areas of the two prism side surfaces.
According to a second aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the first aspect of the invention, the preventive means is means formed by chamfering the vertical angle portion of the prism in such a manner that the vertical angle adjacent areas of the two prism side surfaces are cut away from the prism.
According to a third aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the first aspect of the invention, the preventive means is a light shielding member disposed in the vertical angle adjacent areas of the two prism side surfaces so as to cover them.
According to a fourth aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the third aspect of the invention, the light shielding member is formed integral with the case.
According to a fifth aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the third aspect of the invention, the light shielding member is formed integral with a prism fixing member for fixing the prism to the case.
According to a sixth aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the second aspect of the invention, the preventive means further includes a light shielding member disposed at the chamfered area of the prism. The light shielding member may be formed integrally with a prism fixing member.
According to a seventh aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the sixth aspect of the invention, the light shielding member is formed integrally with a front portion of the case and blocks light from entering the prism through the chamfered surface.
According to an eighth aspect of the invention, in a vehicle periphery visual confirming apparatus as set forth in the sixth aspect of the invention, the prism fixing member is formed integrally with the case.